The theoretical analysis of concentration-patterns of frontal adsorption and desorption dynamics of mixtures in a fixed bed for the Langmuir adsorption isotherms is considered for the equilibrium and non-equilibrium models. For the equilibrium model, the concentration-constant-patterns and concentration-proportional-patterns may be described by using the Riemann invariants R(k) and H-1 invariant analytical expressions which are found. The methods of calculation of adsorption and desorption isotherms based on the use of outlet-concentration-distributions are developed. Adsorption and desorption isotherms of mixtures of the water soluble associative polymer for two end-groups (R:= C16H33 and R:= H) onto particulate surfaces of titanium dioxide are obtained. It is shown that the method developed can be used to measure the adsorption and desorption isotherms over a wide range of associative polymer concentrations.